The present invention relates to laser-weldable flexible tubing that is particularly well suited for use in the delivery of therapeutic solutions such as peritoneal dialysis solutions.
It is known to use medical containers with tubing for various medical procedures such as kidney dialysis, intravenous delivery of therapeutic fluids, delivery of nutritional fluids; delivery of blood, blood components, and blood substitutes. Fluid containers and tubing are also widely used in other industries such as the food industry and the chemical industries.
For example, flexible medical tubings are used in systems for treating renal disease. In renal failure of any cause, there are several physiological derangements. The balance of water, minerals and the excretion of daily metabolic load is no longer possible in renal failure. During renal failure, toxic end products of nitrogen metabolism (urea, creatinine, uric acid and others) can accumulate in blood and tissues.
Kidney failure and reduced kidney function have been treated with dialysis. Dialysis removes waste, toxins and excess water from the body that would otherwise have been removed by normal functioning kidneys. Dialysis treatment for replacement of kidney functions is critical to many people because the treatment is life saving. One who has failed kidneys could not continue to live without replacing at least the filtration functions of the kidneys. Hemodialysis and peritoneal dialysis are two types of dialysis therapies commonly used to treat loss of kidney function.
In general, hemodialysis treatment removes waste, toxins, and excess water from the patient's blood. The patient is connected to a hemodialysis machine and the patient's blood is pumped through the machine. Catheters are inserted into the patient's veins and arteries to connect the blood flow to and from the hemodialysis machine. As blood passes through a dialyzer in the hemodialysis machine, waste, toxins, and excess water are removed from the patient's blood and the blood is infused back into the patient. Many tubes are used in the process that must be connected or disconnected. Hemodialysis treatment lasts several hours and is generally performed in a treatment center about three or four times per week.
Peritoneal dialysis, typically, utilizes a dialysis solution, or dialysate, which is infused into a patient's peritoneal cavity. The dialysate contacts the patient's peritoneal membrane in the peritoneal cavity. Waste, toxins and excess water pass from the patient's bloodstream through the peritoneal membrane and into the dialysate. The transfer of waste, toxins and water from the bloodstream into the dialysate occurs due to diffusion and osmosis, i.e., there is an osmotic gradient across the membrane. The spent dialysate is drained from the patient's peritoneal cavity to remove the waste, toxins and water from the patient. After the spent dialysis is drained, it is replaced with a fresh dialysate solution.
While the present invention has application in connecting or disconnecting tubes for medical procedures, the following discussion focuses, as an example, on a particular tube connection and disconnection processes performed during peritoneal dialysis. Numerous tubes are used in the process that must be connected or disconnected. In peritoneal dialysis, patients have a catheter implanted in their peritoneal cavity with an end protruding from the patient. The protruding end of the catheter terminates with a section of tubing known as a transfer set. The transfer set is typically made from a silicone material and must be periodically replaced say every several months. The transfer set is provided to connect the patient to dialysate fluid bags or discharge bags. The transfer set typically has a spike that connects to an access port positioned in a tube associated with the drain bag or dialysate solution bag (dialysate set). In general, the patient manually stabs the port with the spike to connect the transfer set to the dialysate set. The patient connects the tube in the transfer set to a drain to allow spent dialysate fluid to drain from the peritoneal cavity. Next, the patient is connected to a bag of fresh dialysate and manually infuses the fresh dialysate through the catheter and into the patient's peritoneal cavity. When the patient completes treatment, the port is pulled off the spike and a cap is placed on the spike until the patient is ready for the next treatment. When the patient disconnects the catheter from the fresh dialysate bag, the dialysate dwells within the peritoneal cavity to draw waste, toxins and excess water from the patient's bloodstream to the dialysate solution. After the dwell period, the patient repeats the manual dialysis procedure and drains the spent dialysate from the peritoneal cavity.
Accordingly, during dialysis treatments such as those described above, the patient is required to connect and disconnect the catheter and transfer set from the fill or drain line (or tube) a number of times. Some devices are available today to assist the patient during the process when using specialized sterilization equipment. However, by and large, these connections and disconnections are performed manually.
One such device, incorporates a heated wafer or hot knife that physically contacts the tubing to cut it by melting the tube and joining two tubes together or melt-sealing the tube ends. Typically, heated wafer applications involve a “melt and wipe” process. In peritoneal dialysis, for example, a patient must drain spent dialysate or replenish his/her peritoneal cavity with fresh dialysate. To this end, the patient must connect the transfer set tubing to a tube extending from either a drain bag or a bag containing fresh dialysate. In one “melt and wipe” process, the transfer set tubing is bent in a U or V-shape to fit into a U or V-shaped tube holder. Similarly, the bag-side tube is bent in a U or V-shape to fit into another U or V-shaped tube holder adjacent the first tube holder. A heated wafer moves across the space between the two tube holders and physically contacts the tubing at the bend junction of the U-shape or V-shape. As the heated wafer contacts the tubing, it melts the tube at the bend junction of the U-shape or V-shape. The wafer then wipes the melted tubing material and removes the material from the area between the tube holders. The two holders are brought together and two connections are made. In the first connection, the transfer set tubing is connected to the bag-side tube and the dialysis process is ready to begin. In the second connection, the wasted tube material from the transfer set tubing and the bag-side tube is connected together and discarded.
In order to disconnect the patient from the bag, hot knives are used to cut the tube. An example of a known disconnecting process with the hot knife involves two tubes that are placed side by side across two tube holders. One of the tubes is a short tube having two sealed ends. Generally, the tube holders include a ridge at one end of the tube holder to flatten a portion of the tube to stop fluid flow. The hot knife severs each tube into two pieces. After the hot knife cuts the tube, one of the tube holders moves in relation to the other tube holder. The tubing is “swapped,” realigned with one of the cut portions of the short tube, and connected to it—thus, a disconnection is made between the patient and the bag.
These devices have a relatively low level of reliability due to the inconsistency in melting and cutting processes. This inconsistency can result in imperfect seals, leading to leaks, bacterial infiltration and, ultimately, the patient may well experience, among other things, infection or peritonitis. Also, none of these known methods inspect the integrity of the weld formed between the two tube ends during the connection process. Thus, users must rely on their own visual inspection of the weld.
Moreover, these devices are not user friendly. Often times, patients that need dialysis treatment are visually or otherwise impaired. For example, some dialysis patients experience manual dexterity problems. Many of the known processes involve a great deal of human interaction with loading the tubes into the tube holders. Also, the equipment should be cleaned and the heated wafer replaced after each use to avoid contamination. Thus, this is a difficult process for visually impaired patients and those with poor manual dexterity.